1. Field of the Invention
The present invention relates to an illuminating apparatus, in particular to a ring-shaped illuminating apparatus with variable projection angle for photography.
2. Description of Related Art
Macro photography (or close-up photography) is to capture images of objects by photographic devices like cameras at a distance within about 30 cm. In recent years, applications of macro photography extend from ecological photography of animals and plants to high-magnification visual inspection and non-destructive inspection required in manufacturing processes of industrial products.
In the field of macro photography, the requirement of the illumination for objects is more important in comparison with normal photography. Since conventional ring-shaped flashlights installed on the lenses can not provide steady illumination, but can only provide instant flash illumination on the objects at the moment of shooting images, users can not predict if there will be enough illumination on the object before shooting. Therefore, users have to adjust the aperture and shutter speed of cameras in advance only based on their own experience, which leads to a higher failure rate of shooting.
Recently, many ring-shaped lights adopt cold cathode fluorescent lamps (CCFLs) or light emitting diodes (LEDs) as their light sources, which can provide steady illumination on objects for users to observe before shooting images. However, since the objects are very close to the ring-shaped light in the application of macro photographing, the light projected by the ring-shaped light will cause a non-uniform brightness distribution with a darker center portion and a brighter outer portion.